The minimal invasive periacetabular osteotomy PAO is a joint-preserving procedure that effectively corrects hip dysplasia, provides pain relief, improved radiographic results and a low rate of complications. The aim of this doctoral doctoral dissertation was to examine biological changes in bone, cartilage and blood perfusion after PAO in patients with hip dysplasia. Furthermore, to investigate the relationship between the acetabular angles and health-related quality of life (QoL) after PAO. And finally, to study the level of radiation to the surgeon during PAO.
Chapters 2 to 6 investigate the first research question “Which biological changes take place in bone and cartilage 2-10 years after PAO?”. In Chapter 2, a precise and efficient method for estimating the thickness of the articular cartilage in the hip joint is developed using stereologic methods and Magnetic Resonance Imaging (MRI). The metod is applied on 26 patients scheduled for PAO. In chapter 3, a cohort of patients with hip dysplasia are followed with Dual-energy X-ray absorptiometry (DXA) prior to and 1 and 2½ years after PAO to investigate changes in acetabular bone mineral density after PAO. Moreover, to examine whether bone mineral density correlates with postoperative migration of the osteotomised acetabular fragment measured with radiostereometric analysis. Chapter 4 explores the same cohort of patients with MRI and examines how many patients had acetabular or femoral head cysts and investigates whether the volume of the subchondral bone cysts change after PAO. In chapter 5, it is examined whether changes in the thickness of the cartilage in the hip occur after PAO. Further, it is explored how many patients had an acetabular labral tear and whether labral tears are associated with thinning of the cartilage after PAO. Chapter 6 investigates the long-term changes in cartilage thickness and volume of subchondral bone cysts measured with MRI and stereology 10 years after PAO.
The second research question “What is the level of changes in blood perfusion and bone formation in the acetabular fragment after PAO?” is evaluated in chapter 7. Blood perfusion and bone formation is quantified before and after PAO by positron emission tomography (PET) combined with computed tomography (CT).
Chapter 8 evaluate the third research question “Is there a relationship between the radiological parameters and health-related QoL after PAO” The Short Form-36 and Beighton questionnaires are collected to investigate the health-related QoL for patients with hip dysplasia operated with PAO and to investigate whether QoL is associated with the acetabular angles or hypermobility.

In chapter 9, the fourth research question is investigated “Does the level of radiation during PAO impose a health risk to the surgeon?” The radiation exposure to the orthopaedic surgeon and to the surgeon’s fingers, thyroid gland, and forehead during intraoperative fluoroscopy in PAO is measured with thermo luminescent dosimeters (TLD).
Finally, the results of the above described studies and future studies are discussed in chapter 10 and 11.